A black electrochromic device based on a CuI film for energy-efficient applications

Abstract

Benefiting from the diversity of electron orbitals, such as s, p, and d orbitals associated with a metal center, as well as the various molecular orbitals associated with organic ligands, metal–organic electrochromic materials can achieve different colors in a single device. Moreover, as both the tunability of organic materials (ligand) and the bistability of inorganic materials (metal ions) can be realized by these materials, significant research efforts have been devoted to their study. Metal–organic electrochromic materials with variety bright colors have been developed based on the dynamic coordination of metal ions and molecular switches as well as semi-solid devices. However, the optical modulation ability is limited by an insufficient content of metal ions. In this work, the dynamic coordination between Cu ions and molecular switches which consisted of 2-anilino-6-(dibutylamino)-3-methylfluoran and polymethyl methacrylate (ODBMA) was verified in the solid phase. Based on this coordination, a cuprous iodide (CuI) film was successfully synthesized on an indium tin oxide electrode. Owing to its bistability, the fabricated electrochromic device presents considerable potential for the development of energy-efficient smart windows.